Changing Circumstances
by Dallimater
Summary: SEQUEAL TO WHAT IF. Phineas still hasn't learned not to mess with the space time continuum, and this time he does it for Isabella, but just ends up putting her in harms way as well as Izzy. Now he needs help from Phin and Izzy, who are having their own major problems. their troubles mix and people get hurt. can they survive? T for violence. Phinbella and Phizzy.
1. Chapter 1

**I AM BACK YO. after months of practically disappearing on FF I have returned with the sequel to What If! **

**I'll keep this short so hope you all enjoy ;) oh and...**

**NOTCIE: IF YOU HAVE NOT READ WHAT IF THAT I SUGGEST YOU DO THAT BEFORE READING THIS OR YOU WILL BE CONFUSED.**

**ok so no need for disclaimer yet but I'll do it anyways: I do not own Phineas and Ferb xP**

* * *

The night was dark, pitch black. The new summer breeze flew through the air, guiding the clouds that hid the stars and the moon, only to make it blacker. But luckily, tonight the comforting glow of the nightly heavens were not needed, for a shadowy figure that stood on the roof tops would prefer to be hidden in the lonely darkness. The figure was a teenager, but no ordinary adolescence. This one had endured pain for years, and had to confront even more when trying to get out of it. The teen's suffering life came to an end less then a year ago with the help of some friends, only to be replaced with a complicated one. And now look where this life has gotten this poor soul, on a rooftop, dressed in a black hoodie and jeans, with a platypus pup beside the figure.

The pup looked up at the teenage girl, uncertainty in his eyes. She looked down at him, an equally doubtful look on her face. "Don't worry." She whispered. "It has to get done, or your owner will become disappointed, and we don't want that."

The platypus rolled his eyes. Knowing that 'disappointed was a _huge_ understatement. The girl sighed. "PJ, don't exaggerate, he's gotten better with this anger of his… now lets get to business before he _does_ get anger. And we all know he would only be angry at you."

PJ nodded roughly and looked at the ongoing houses ahead. He then blinked and chattered nervously. A device that looked like a mic processed the monotreme's sounds and played it again in English "_You sure you want to do this Izzy?_" He asked with his natural born Australian accent.

Izzy nodded. "Of course I do. Its what I've been training for. Now don't waste your mic's battery and switch your hat to stealth mode." PJ sighed and did as he was told, touching a sensor on his flipped cap, making it change from bright red to black.

"_Ok, lets do this_."

The girl nodded reluctantly and looked down at her "utility" belt. She took a small, phone like device from it and held it up to her mouth. "Go to: Flynn Corporations old warehouse, Frank Flynn's office." Izzy closed her eyes and PJ quickly took hold of her leg as the phone beeped and they were transported to said destination. When she opened them again, she found herself and the platypus one foot away from her actual destination and still outside, but this time ten stories up with nothing under their feet. They started falling, both trying to contain their screams to prevent unwanted attention. Izzy quickly touched a sensor on her belt and a grappling hook shot out and grabbed the sill at the bottom of the window of Frank's office. The wind was knocked out of Izzy and the rope tightened up around her waist.

"_Izzy! Are your ok?"_ She heard PJ as he held onto her feet.

"I'm… fine." She breathed, sounded winded." Stupid prototype. I'm going… to kill Ferb… for this."

"_Just_ _focus."_

"I know." She climbed up the rope to the thin windowsill and sighed in relief. Pushing the window open quietly, she climbed inside the dark room with PJ following suit. The sixteen-year old put on her night vision glasses, for the room was as dark as outside and the lighting didn't work. She quickly looked around, the place looking like an abandoned crime scene, with signs numbering evidence like the blood on the floor and yellow police tape covering the closed door. Ever since the "assassination" on Frank Flynn the warehouse was closed down. And since they couldn't find a trace of evidence against someone they closed the case altogether. Izzy looked away form the sight she never wanted to remember and searched the walls where her friend said would be a picture, and she found it.

The large family photo of the Flynn family looked depressing and lonely, not that Izzy cared. She pressed the ball the little boy was holding, sure enough, just like her friend said, it turned out to be a button and the framed photo opened up like a door. And inside was her prize, a laptop. She pulled and out and set it on the dusty wood table. Izzy pulled out a special transportable USB and stuck into the slot on the side of the computer. It immediately charged up and turned on, but the only way to get into the laptop was 5 levels of difficult passwords no one knew besides the deceased Frank himself. Luckily Baljeet programmed the USB to automatically hack those passwords and allow easy access. After the hacking ceased and she was in, Izzy immediately opened the file labeled "Agent Files". She looked through the files and transferred the documents "Phin(eas) Flynn", "Baljeet Tjinger", and "Buford Van Stomm" to the USB and then went to the "Victim Files" file. Then she transferred also "Ferb Fletcher".

"That should be it." She whispered to PJ, who was keeping guard.

_"Sssh!"_

"P-"

_"I said shush! I though I heard some voices…"_

"PJ that's ridiculous, their should be no one he-"

Suddenly the voices got louder until it reached the room. Their eyes widened and the door opened and three people who looked exactly the same looked in and pointing flashlights at them, equally surprised to see Izzy and PJ here.

"Who are you?!" They all said at the same time with the same German accent. One of the men looked like a pharmacist, with a lab coat, black sweater, grey kakis and black dress shoes. Another looked like a dictator with a eye-patch going over one of his eyes, a goatee and wearing a black leather jacket and black jeans. The last looked like a professor with a grey suit coat and pants, red vest and a white tucked-under tie. All had messy brown hair, brown eyes and a pointed nose.

"Is that a platypus?" Sir Pharmacist asked.

"This was unexpected." Muttered Dr. Professor.

"Shut up you two and GET HER!" exclaimed Mr. Dictator as he clenched his fists.

They all ran towards her, but she took the USB out and slammed the laptop shut, quickly taking a knife out of her belt and stabbing the computer, making sparks fly.

"NO! She destroyed the computer!" Dr. Professor cried out.

Before they could get their hands on her or the USB, she picked up PJ and jumped out the window. They fell until Izzy could reach her belt and touch a sensor. Soon a glider that looked like bat wings popped out and slowed them down. They still it hit the ground pretty hard, giving Izzy a good gash on her knees. She ignored the pain and stood up, quickly grabbing the transporter.

"Go to: Phin..._ pant_… Flynn" With that she and the platypus disappeared into the night, leaving the mad doctors screaming out the window in disbelief.

* * *

Phin set his hand rifle onto the stand and looked up excitedly at the target. _Finally, a chance to try my new attachment. _He thoughtand he lowered his head down to the scope, aiming at the bullseye. _"shoot o-"_ His thoughts were interrupted as Izzy teleported not next to him like she was supposed to, but on him. He yelled in surprised and she yelped in pain as the two fell to the ground.

"What the hell Izzy I could have killed you!" He yelled as he stood up and also helped her to her feet."

"I'm sorry… Phin… but… I… have… the…" Suddenly the adrenaline rushed out of her and the pain of the fall trailed up her body. Not able to take it, she crashed back to the ground and everything went black.

* * *

**Long prologue but who gives a crap I'm going to bed! bai bai hope you enjoyed and REVEIW! :D**


	2. Chapter 2

"Happy Father's day!" Sixteen-year-old Phineas Flynn exclaimed as he reached the bottom of the stairs. His stepfather, Lawrence, looked up from the newspaper and smiled at the two teenage boys that walked over to him.

"Thank you Phineas." He said with his thick British accent, accepting a hug Phineas and Ferb gave him.

"So what do you and Mom have planned today?"

"Well, actually," Lawrence started, turning his head to his wife who was finishing up some coffee. "Your mother decided to surprise me today and bought two tickets to California, where the annual antique convention of the year is being held."

"Really?! That's awesome! How long will you be gone?" Phineas asked as he sat down.

"A week. I sure hope that's ok with you two."

"Its fine." Ferb replied with a smile.

"Of course! You two should go and have some fun. When are you leaving?"

"We are heading to the airport in a couple hours." Linda replied as she finished off her coffee.

"Ok. Just come and find us when you're leaving so we can say goodbye."

"Of course. But where are you going?"

"To the park to meet Isabella and Vanessa for a double date." Phineas answered and he played with the string on his hoodie.

"Oh how nice!" Linda exclaimed. "Its astonishes me you two have girlfriends already, at such young ages!"

"Mom," Phineas laughed. "I'm sixteen-"

"And I'm seventeen." Ferb added.

"Right, and he's seventeen. I wouldn't call that young." Phineas let out another chuckle.

"Oh I know, but you two will always be young to me." Their mom smiled and got up from her chair to put her mug in the sink.

"And I'll always feel young!" The redhead said with a smile. He turned to his brother and motioned for him to follow. "C'mon Ferb! I know what we're gonna do today! Hey? Where's Perry?"

* * *

It was now noon and the stepbrothers had finished the project, had some fun on it, and then it vanished. Same thing that happens every day, not that they minded. Their parents had said good-bye to them and now the two were left alone in the backyard with their two friends, Buford and Baljeet.

"What a fun day!" Phineas exclaimed and he sat done under his tree. Ferb nodded and copied his brother's actions, sitting beside the redhead.

"Aren't you two supposed to be getting prepared for your dates?" Baljeet asked.

"We are ready! We aren't doing anything fancy, so there is no reason to prepare for it." Said Phineas.

Buford huffed. "Ya well apparently Isabella thinks differently. Girly hasn't come over once today! She has probably been getting ready for your date this whole time."

"Ya now that you mention it, Isabella hasn't come over today. It feels so weird! Not having her say 'Wha'cha dooin?' in the morning." Phineas' eyes turned thoughtful. "But your probably right Buford, she has probably just been getting prepared this whole time. You know how girls are."

"Are you stereotyping girls, Phineas?" They heard a womanly voice come from the entrance of the gate. They all turned their heads towards Vanessa Doofenshmirtz as she flicked her hair and crossed her arms. Ferb immediately stood up and was by her side.

"You ready to go?" He asked her as he took her hand.

"Of course." Vanessa then looked at Phineas. "And where is your girlfriend? Isn't she the 'right-on-time' type girl?"

"Ya she is pretty punctual. I have no idea what could be taking her this long. I should probably go get her." Phineas suggested as he started to the street.

"We'll meet you at the park, Phineas." Ferb said as he and Vanessa walked out as well. "By the pond."

"Ok see you there!" Phineas waved as he crossed the street and walked up to Isabella's front porch. He knocked a couple times and waited patiently for someone to come and answer.

Not long after Phineas knocked he heard light footsteps heading towards him. Isabella opened the door, but what Phineas saw was not what he expected. Granted, she was wearing her normal summer attire, but her expression was sensitive and her eyes were sad. Once she saw Phineas she immediately turned shocked. "Oh Phineas!" She exclaimed. "I'm so sorry, I forgot about the date! Come in and I'll go get my shoes."

As Isabella rushed away he walked into the house, closing the door behind him. His expression was concerned and he started looking for his girlfriend. "Isabella?" He called.

"In here!" He walked towards the voice and saw her in the laundry room fumbling with her Converse sneakers. "Again, Phineas, I'm really sorry. I don't know what's gotten into me."

"It's fine Isabella." He responded with a smile. "But why are you so sad?"

She quit stumbling around and sighed slowly. "How is it that when you were young you couldn't determine my feelings for crap and now you can read me like a book?"

Phineas shrugged. "Boyfriend intuition. Now what's wrong?"

The girl pursed her lips and stood up straight. "You know its Father's Day right? Well you know my father died by a car accident when I was young, so this is kind of a morbid day for me. The only memory I have of him is one Father's Day when we made him breakfast and he was so happy. That was such a special day because that was the first time he said he was proud of me. But now he's gone and I can't make any more memories with him like you can with your stepdad…"

Phineas looked at her sadly, surprised how strong she is during this situation, considering he would have been crying like a baby. "Oh Isabella." He pulled her into a hugged and she gladly accepted it.

"But-" She started as she pulled away from his embrace. "Its ok, because I have you to cheer me up! So let me just put on my shoes and we can meet Ferb and Vanessa." She seemed genuinely cheerful, but Phineas could still see the hint of sadness in her eyes.

"Wait Isabella…" Phineas muttered as the imaginative gears in his brain started to turn. "I think I have an idea."

"Oh?" She looked at him curiously. "What is it?"

An idea popped in his brain and he jumped. "That's it! I know what you and I are going to do today!"

"What is it!?" Isabella asked, quite excited.

"We are going to build a time machine and get your dad back!" He immediately pulled out his phone and dialed Ferb number. "Ferb? We aren't gonna be able to make it. No, Isabella is fine but I have something I need to do. Thanks bro!" Phineas hung up and looked at her. "C'mon Isabella! While its still daylight!"

* * *

Phin slammed his fist down on the table, angered by the fact that his girlfriend was injured during the mission. PJ jumped, almost dropping his banana he was enjoying. "Baljeet!" He screamed. "Where are those results?!"

Baljeet ran in with a clipboard, Gretchen not far behind. "Izzy had suffered hairline fracture in her leg, which was healed by the Recuperate-or. She is also a bit dehydrated from lack of fluid intake before the mission."

Phin's eyes shot daggers at the boy who back up slowly, afraid of what the redhead might do. Gretchen quickly stepped forward to avoid a mess. "In other words… She's fine and she is awake as well. You can go and visit her now."

Without another word, Phin was at his feet and rushing to the elevator. He stepped in and pushed the button leading to the floor Izzy was currently staying at. The elevator shot up and the boy waited impatiently. Wondering where Phin and the gang's HQ is? Well they refurbished Perry's old underground lair and made it their own.

Phin heard a 'ding' and the doors opened. The elevator was quickly unoccupied as the teenager ran out and down the metal hallway. He passed door after door and it never seemed to end until he reached the room he was looking for. Without knocking he burst through and looked at the bed where an ebony-haired girl sat. She looked up and her ocean blue eyes met his navy ones. Phin was quickly at Izzy's side. "You're ok, right?" He asked.

"I'm fine." She squeaked, her voice raspy and small from lack of water. "It's nothing serious."

"I heard."

Izzy quickly shook off this conversation and changed the subject. "There is something bad I need to tell you."

Phin's eyes turned serious. "What is it?"

"W-when I was there, these three men who looked exactly the same barged in. They were looking for the laptop, which I destroyed by the way. It was so strange, you think they were triplets?"

Phin bit his lip and pushed that unanswerable question aside. "What did they look like?"

"They all had brown messy hair, long pointed nose, pointed chin and bulgy eyes. They also had a German accent, if this means anything."

"Oh no…" Phin muttered as he stood up and put his hand over his eyes.

What is it?" Izzy asked.

"That man. That man was Heinz Doofenshmirtz, My father's business partner."

* * *

**ahhh... ummm ^^; 5 months since I updated... that's pretty long.**

**Would it help if I said I was extremely busy this summer? :P I had Drivers ed for a month... I went to to NY for 2 week and Florida for 1. I also had a bad case of writers block xPPP so ya feel free to kill me ****_after _****the sequel**

**AND I WOKE UP AT TWELVE AT NIGHT TO WRITE THIS XD took me three hours I was so freaking tired**

**onto reviews:**

**Robot Wolf 26X: indeed!**

**Axis22: Haha I would forgot about it too if it took me this long to update ^^;**

**14AmyChan: looks like you summed up the prologue pretty well! XD **

**writer-person2: Thanks!**

**Loveloo: Glad to see your a fan! :D**

**babybird17: lolwut**

**PianoMan5: lol ya its been a while I bet most of you had to reread the first the first book xP**

**FanFicCriTicTheThird: lol glad to see you happy happy! XD maybe it will be fatal, maybe it won't :3**

**Guest: holy crap o.o that's not a lot of sleep at all**

**Sabrina: well hope you're satisfied with this! ^^**

**What'cha doin: Glad to see your remembered What If seeing as it has been a while XDD **

**Phineas and Ferb Characters (c) Dan and Jeff**


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